Cyclothymia (/ˌsaɪkloʊˈθaɪmiə/), also called cyclothymic disorder, is a type of chronic mood disorder widely considered to be a more chronic but milder or subthreshold form of bipolar disorder. Cyclothymia is characterized by numerous mood swings, with periods of hypomanic symptoms that do not meet criteria for a hypomanic episode,  alternating with periods of mild or moderate symptoms of depression that do not meet criteria for a major depressive episode.
An individual with cyclothymia may feel stable at a baseline level but experience a noticeable shift to an emotional high during subthreshold hypomanic episodes of elation or euphoria, with symptoms similar to those of mania but less severe, and often cycle to emotional lows with moderate depressive symptoms. To meet the diagnostic criteria for cyclothymia, a person must experience this alternating pattern of emotional highs and lows for a period of at least two years with no more than two consecutive symptom-free months. For children and adolescents, the duration must be at least one year. 
While diagnosis of cyclothymia is becoming more common,  it is not as frequent as that of bipolar disorder. Diagnosis of cyclothymia entails the absence of any major depressive episode, manic episode or mixed episode, which would qualify the individual for diagnosis of other mood disorders. When a major episode manifests after an initial diagnosis of cyclothymia, the individual may qualify for a diagnosis of bipolar I or bipolar II disorder. Although estimates vary greatly, 15–50% of cases of cyclothymia later advance to the diagnostic criteria for bipolar I and/or bipolar II disorder (with cyclothymic features).  Although the emotional highs and lows of cyclothymia are less extreme than those of bipolar disorder, the symptomatology, longitudinal course, family history and treatment response of cyclothymia are consistent with bipolar spectrum. 
Lifetime prevalence of cyclothymic disorder is 0.4–1%. 
Frequency appears similar in men and women, though women more often seek treatment. People with cyclothymia during periodic hypomania (euphoria) tend to feel an inflated self-worth, self-confidence and elation, often with rapid speech, racing thoughts, not much need to sleep, increased aggression and impulsive behavior, showing little regard for consequences of decisions—but may sometimes be somewhat, fully or hyper-productive for a period of several days at a time. 
Cyclothymia is derived from the Greek word κυκλοθυμία (from κ κλος kyklos, “circle”  and θυμός thymos, “mood, emotion”).  Therefore, it means “to cycle or circle between moods or emotions”.
Cyclothymia is characterized by short cycles of baseline, stable periods of not over two months and numerous swings between depression and hypomania that fail to meet the severity of sustained duration criterion for major affective syndromes for at least two years. 
Depressive/dysthymic episodes. Symptoms of the depressive/dysthymic phase include difficulty making decisions, problems concentrating, poor memory recall, guilt, self-criticism, low self-esteem, pessimism, self-destructive thinking, constant sadness, apathy, hopelessness, helplessness and irritability. Also common are quick temper, poor judgment, lack of motivation, social withdrawal, appetite change, lack of sexual desire, self-neglect, fatigue, insomnia and sleepiness. 
Hypomanic episodes. Symptoms of the hypomanic episode include unusually good mood or cheerfulness (euphoria), extreme optimism, inflated self-esteem, rapid speech, racing thoughts, aggressive or hostile behavior, lack of consideration for others, agitation, massively increased physical activity, risky behavior, spending sprees, increased drive to perform or achieve goals, increased sexual drive, decreased need for sleep, tendency to be easily distracted, and inability to concentrate. 
The following are the revised criteria for a diagnosis of cyclothymic disorder (DSM-IV-TR 301.13) from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR): 
A. For at least 2 years (1 year in children and adolescents), the presence of numerous periods with hypomanic symptoms and numerous periods with depressive symptoms that do not meet criteria for a Major Depressive Episode
B. During the above period, the person has not been without the symptoms in A for more than 2 months in the 2-year period
C. No Major Depressive Episode, Manic Episode, or Mixed Episode has been present during the first 2 years of the disturbance.
D. The symptoms in Criterion A are not better accounted for by Schizoaffective Disorder and are not superimposed on Schizophrenia, Schizophreniform Disorder, Delusional Disorder, or Psychotic Disorder Not Otherwise Specified.
E. The symptoms are not due to the direct physiological effects of a substance (e.g. drug of abuse, a medication) or a general medical condition (e.g., hyperthyroidism).
F. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
The DSM-IV-TR notes that the mood disturbance must be not severe enough to constitute a full-fledged manic or major depressive episode. The diagnosis requires that there be periods of both hypomania and depression and that periods of normal mood not last longer than 2 months.
The DSM-IV-TR also notes that Cyclothymia and borderline personality disorder share similar features and that individuals can be diagnosed with both BPD and Cyclothymia depending on the symptoms they present.
Diagnosis of cyclothymia is difficult for a number of reasons. The depressive-dysthymic episode of cyclothymia is also a diagnostic feature of many disorders, including adjustment disorders, personality disorders, psychotic disorders, and other mood disorders.  Since depression can be triggered or exacerbated by life events and circumstances, the diagnosing clinician must determine when it is an acceptable response and when it is pathological.
Symptoms described in the hypomanic episode are also commonly associated with ADHD, such as increased energy, distractibility and impulsive or risk-seeking behavior.  This is of particular concern in child psychiatry because symptoms, especially hyperactivity, may be counted twice toward both disorders or may inflate the prevalence of ADHD.  While childhood ADHD often presents with hyperactivity, adult ADHD often does not. The unstable lifestyle often found both in people with ADHD and in those with cyclothymia can cause problems for differential diagnosis. Important distinguishing factors include that ADHD is characterized mainly by problems with concentration and memory, while cyclothymia mainly by periods of elevated self-confidence and elation. 
Whether subtypes of bipolar disorder, such as cyclothymia. truly represent separate disorders or are part of a unique bipolar spectrum is still debated in research.  Cyclothymia is typically not described in research studies or diagnosed in clinical settings, making it less recognizable and less understood by professionals.  This absence of cyclothymia in research and clinical settings suggests that cyclothymia is either being diagnosed as another mood disorder or as a non-affective psychiatric disorder or not coming to scientific or clinical attention  due to a lack of diagnostic clarity or because the nature of cyclothymia is still highly contested. Additionally, the current diagnostic criterion for cyclothymia emphasizes that symptoms are persistent, which suggests that they are enduring traits rather than a psychological state, thus, it has been argued that it should be diagnosed as a personality disorder. Since the symptoms tend to overlap with personality disorders, the validity and distinction between these two diagnostic categories has been debated. 
Lastly, the tendency of cyclothymia to be comorbid with other psychiatric disorders makes diagnosis difficult. 
These issues prevent consensus on the definition of cyclothymia and its relationship with other psychiatric disorders among researchers and clinicians. This lack of consensus on an operational definition and symptom presentation is especially pronounced with children and adolescents because the diagnostic criteria have not been adequately adapted to take into account their developmental level.  However, there has been a shift from categorical models of bipolar related disorders toward a dimensional model, which is intended to address some of these issues.
This disorder is common in the relatives of patients with bipolar disorder, and some individuals with cyclothymia eventually develop bipolar disorder themselves. It may persist throughout adult life, cease temporarily or permanently, or develop into more severe mood swings, meeting the criteria for bipolar disorder or recurrent depressive disorder in some cases. 
The exact cause of cyclothymia is unknown. It is known that major depression, bipolar disorder, and cyclothymia often occur together within families.  There may be a genetic component to cyclothymia: In one study, it was found that an individual is 2–3 times more likely to have the disorder if an identical twin is affected. 
Not to be confused with Semantic pragmatic disorder, Schizoid personality disorder, Schizoaffective disorder, or Asperger’s syndrome.
Schizotypal personality disorder (STPD) or schizotypal disorder is a mental disorder characterized by severe social anxiety, paranoia, and often unconventional beliefs. People with this disorder feel extreme discomfort with maintaining close relationships with people, mainly because they think that their peers harbor negative thoughts towards them, so they avoid forming them. Peculiar speech mannerisms and odd modes of dress are also symptoms of this disorder. In some cases, people with STPD may react oddly in conversations, not respond, or talk to themselves. 
They frequently interpret situations as being strange or having unusual meaning for them; paranormal and superstitious beliefs are common. Such people frequently seek medical attention for anxiety or depression instead of their personality disorder. 
Schizotypal personality disorder occurs in approximately 3% of the general population and is slightly more common in males. 
Although listed in the DSM-IV-TR on axis II, schizotypal personality disorder is widely understood to be a “schizophrenia spectrum” disorder that is on axis I. Rates of schizotypal personality disorder are much higher in relatives of individuals with schizophrenia than in the relatives of people with other mental illnesses or in people without mentally ill relatives. Technically speaking, schizotypal personality disorder may also be considered an “extended phenotype” that helps geneticists track the familial or genetic transmission of the genes that are implicated in schizophrenia. 
Social and environmental
There is now evidence to suggest that parenting styles, early separation, trauma/maltreatment history (especially early childhood neglect) can lead to the development of schizotypal traits.  Neglect or abuse, trauma, or family dysfunction during childhood can increase the risk of developing schizotypal personality disorder.  Over time, children learn to interpret social cues and respond appropriately but for unknown reasons this process does not work well for people with this disorder. 
Schizotypal personality disorders are characterized by a common attentional impairment in various degrees.  A study suggested that attention deficits could serve as a marker of biological susceptibility to schizotypal personality disorder.  The reason is that an individual who has difficulties taking in information may find it difficult in complicated social situations where interpersonal cues and attentive communications are essential for quality interaction. This might eventually cause the individual to withdraw from most social interactions, thus leading to antisocialism. 
Schizotypal personality disorder usually co-occurs with major depressive disorder, dysthymia, and generalized social phobia.  Furthermore, sometimes schizotypal personality disorder can co-occur with obsessive-compulsive disorder, and its presence appears to affect treatment outcome adversely. 
Some persons with schizotypal personality disorders go on to develop schizophrenia,  but most of them do not.  Although STPD symptomatology has been studied longitudinally in a number of community samples, the results received do not suggest any significant likelihood of the development of schizophrenia.  There are dozens of studies showing that individuals with schizotypal personality disorder score similar to individuals with schizophrenia on a very wide range of neuropsychological tests. Cognitive deficits in patients with schizotypal personality disorder are very similar to, but quantitatively milder than, those for patients with schizophrenia.  A 2004 study, however, reported neurological evidence that did “not entirely support the model that SPD is simply an attenuated form of schizophrenia”. 
In case of methamphetamine use, persons with schizotypal personality disorders are at great risk of developing permanent psychosis. 
In most instances, schizotypal personality disorders co-occurs with the schizoid, paranoid, avoidant, and borderline personality disorders. 
In the American Psychiatric Association’s DSM-5, schizotypal personality disorder is defined as a “pervasive pattern of social and interpersonal deficits marked by acute discomfort with, and reduced capacity for, close relationships as well as by cognitive or perceptual distortions and eccentricities of behavior, beginning by early adulthood and present in a variety of contexts.” 
At least five of the following symptoms must be present: ideas of reference, strange beliefs or magical thinking, abnormal perceptual experiences, strange thinking and speech, paranoia, inappropriate or constricted affect, strange behavior or appearance, lack of close friends, and excessive social anxiety that does not abate and stems from paranoia rather than negative judgments about self. These symptoms must not occur only during the course of a disorder with similar symptoms (such as schizophrenia or autism spectrum disorder). 
The World Health Organization’s ICD-10 uses the name schizotypal disorder (F21 ). It is classified as a clinical disorder associated with schizophrenia, rather than a personality disorder as in DSM-5. 
The ICD definition is:
A disorder characterized by eccentric behavior and anomalies of thinking and affect which resemble those seen in schizophrenia, though no definite and characteristic schizophrenic anomalies have occurred at any stage. There is no dominant or typical disturbance, but any of the following may be present: Inappropriate or constricted affect (the individual appears cold and aloof);
Behavior or appearance that is odd, eccentric or peculiar;
Poor rapport with others and a tendency to withdraw socially;
Odd beliefs or magical thinking, influencing behavior and inconsistent with subcultural norms;
Suspiciousness or paranoid ideas;
Obsessive ruminations without inner resistance, often with dysmorphophobic, sexual or aggressive contents;
Unusual perceptual experiences including somatosensory (bodily) or other illusions, depersonalization or derealization;
Vague, circumstantial, metaphorical, over-elaborate or stereotyped thinking, manifested by odd speech or in other ways, without gross incoherence;
Occasional transient quasi-psychotic episodes with intense illusions, auditory or other hallucinations and delusion-like ideas, usually occurring without external provocation. The disorder runs a chronic course with fluctuations of intensity. Occasionally it evolves into overt schizophrenia. There is no definite onset and its evolution and course are usually those of a personality disorder. It is more common in individuals related to people with schizophrenia and is believed to be part of the genetic “spectrum” of schizophrenia.
This diagnostic rubric is not recommended for general use because it is not clearly demarcated either from simple schizophrenia or from schizoid or paranoid personality disorders, or possibly autism and aspergers as currently diagnosed. If the term is used, three or four of the typical features listed above should have been present, continuously or episodically, for at least 2 years. The individual must never have met criteria for schizophrenia itself. A history of schizophrenia in a first-degree relative gives additional weight to the diagnosis but is not a prerequisite.
Latent schizophrenic reactions
Schizotypal personality disorder
Schizoid personality disorder
Asperger’s syndrome (although differentiation may be difficult due to significant common symptoms)
Theodore Millon proposes two subtypes of schizotypal.  Any individual with schizotypal personality disorder may exhibit either one of the following somewhat different subtypes (Note that Millon believes it is rare for a personality with one pure variant, but rather a mixture of one major variant with one or more secondary variants):
There is a high rate of comorbidity with other personality disorders. McGlashan et al. (2000) stated that this may be due to overlapping criteria with other personality disorders, such as avoidant personality disorder, paranoid personality disorder and borderline personality disorder. 
There are many similarities between the schizotypal and schizoid personalities. Most notable of the similarities is the inability to initiate or maintain relationships (both friendly and romantic). The difference between the two seems to be that those labeled as schizotypal avoid social interaction because of a deep-seated fear of people. The schizoid individuals simply feel no desire to form relationships, because they see no point in sharing their time with others.
STPD is rarely seen as the primary reason for treatment in a clinical setting, but it often occurs as a comorbid finding with other mental disorders. When patients with STPD are prescribed pharmaceuticals, they are most often prescribed the same drugs used to treat patients suffering from schizophrenia including traditional neuroleptics such as haloperidol and thiothixene.  In order to decide which type of medication should be used, Paul Markovitz distinguishes two basic groups of schizotypal patients: 
Schizotypal patients who appear to be almost schizophrenic in their beliefs and behaviors (aberrant perceptions and cognitions) – they are usually treated with low doses of antipsychotic medications, e.g. thiothixene. However, it must be mentioned that long-term efficacy of neuroleptics is doubtful.
Schizotypal patients who are more obsessive-compulsive in their beliefs and behaviors – in this case SSRIs, e.g. Sertraline, appear to be more effective.
Lamotrigine, an anti-convulsant, appears to be helpful in dealing with social isolation.
According to Theodore Millon, the schizotypal is one of the easiest personality disorders to identify but one of the most difficult to treat with psychotherapy. [page needed] Persons with STPD usually consider themselves to be simply eccentric, productive, or nonconformist. As a rule, they underestimate maladaptiveness of their social isolation and perceptual distortions. It is not so easy to gain rapport with people who suffer from STPD due to the fact that increasing familiarity and intimacy usually increase their level of anxiety and discomfort. In most cases they do not respond to informality and humor. 
Group therapy is recommended for persons with STPD only if the group is well structured and supportive. Otherwise, it could lead to loose and tangential ideation.  Support is especially important for schizotypal patients with predominant paranoid symptoms, because they will have a lot of difficulties even in highly structured groups. 
Reported prevalence of STPD in community studies ranges from 0.6% in a Norwegian sample, to 4.6% in an American sample.  A large American study found a lifetime prevalence of 3.9%, with somewhat higher rates among men (4.2%) than women (3.7%).  It is uncommon in clinical populations, [clarification needed] with reported rates of 0% to 1.9%. 
A University of Colorado Colorado Springs study comparing personality disorders and Myers-Briggs Type Indicator types found that the disorder had a significant correlation with the Introverted (I), Intuitive (N), Thinking (T), and Perceiving (P) preferences. 
Content is available under CC BY-SA 3.0 unless otherwise noted.